Visual spatial memory in desert ants,Cataglyphis bicolor (Hymenoptera: Formicidae)

Summary For navigation, desert ants apply piloting and dead-reckoning strategies based on terrestrial and celestial visual cues, respectively. Visual spatial memories, rather than general concepts derived from landmark constellations, are most probably used to define points on earth by nearby landmarks. The visual field of a specialized dorsal part of the ant's retina is mapped on to the celestial sphere to consider the possibility that similar mechanisms are used to define directions on earth by exploiting skylight patterns present at infinity.Supported by the Hescheler Foundation (Zurich) and the Swiss National Science Foundation grants Nos 3.529-0.75 and 3.313-0.78.     

The rodent hippocampus and spatial memory: from synapses to systems

Although its operations are not limited to the spatial domain, there is a near consensus that the hippocampus plays a critical role in memory for place. This review aims to explore this role, with a particular emphasis on the functions performed by distinct hippocampal subregions. The use of innovative lesioning techniques, localized pharmacological treatments, and molecular genetic interventions is offering increasingly precise brain-regional specificity and temporal control. Together with the electrophysiological recording of neuronal activity, these techniques are beginning to shed light on the functioning of specific components of the hippocampal circuitry in the different phases of memory – encoding, storage, consolidation, and retrieval. In view of these developments, we examine the involvement of the hippocampus in the encoding versus retrieval of spatial memory, before turning to the issue of long-term information storage and the role of ‘cellular’ and ‘systems’ consolidation processes in the formation of lasting memories. Received 17 July 2006; received after revision 24 October 2006; accepted 16 November 2006     

Furin promotes dendritic morphogenesis and learning and memory in transgenic mice

Furin is a proprotein convertase implicated in a variety of pathological processes including neurodegenerative diseases. However, the role of furin in neuronal plasticity and learning and memory remains to be elucidated. Here, we report that in brain-specific furin transgenic (Furin-Tg) mice, the dendritic spine density and proliferation of neural progenitor cells were significantly increased. These mice exhibited enhanced long-term potentiation (LTP) and spatial learning and memory performance, without alterations of miniature excitatory/inhibitory postsynaptic currents. In the cortex and hippocampus of Furin-Tg mice, the ratio of mature brain-derived neurotrophic factor (mBDNF) to pro-BDNF, and the activities of extracellular signal-related kinase (ERK) and cAMP response element-binding protein (CREB) were significantly elevated. We also found that hippocampal knockdown of CREB diminished the facilitation of LTP and cognitive function in Furin-Tg mice. Together, our results demonstrate that furin enhances dendritic morphogenesis and learning and memory in transgenic mice, which may be associated with BDNF–ERK–CREB signaling pathway.     

E3 ubiquitin ligase RNF13 involves spatial learning and assembly of the SNARE complex

Changes in the structure and number of synapses modulate learning, memory and cognitive disorders. Ubiquitin-mediated protein modification is a key mechanism for regulating synaptic activity, though the precise control of this process remains poorly understood. RING finger protein 13 (RNF13) is a recently identified E3 ubiquitin ligase, and its in vivo function remains completely unknown. We show here that genetic deletion of RNF13 in mice leads to a significant deficit in spatial learning as determined by the Morris water maze test and Y-maze learning test. At the ultrastructral level, the synaptic vesicle density was decreased and the area of the active zone was increased at hippocampal synapses of RNF13-null mice compared with those of wild-type littermates. We found no change in the levels of SNARE (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor) complex proteins in the hippocampus of RNF13-null mice, but impaired SNARE complex assembly. RNF13 directly interacted with snapin, a SNAP-25-interacting protein. Interestingly, snapin was ubiquitinated by RNF13 via the lysine-29 conjugated polyubiquitin chain, which in turn promoted the association of snapin with SNAP-25. Consistently, we found an attenuated interaction between snapin and SNAP-25 in the RNF13-null mice. Therefore, these results suggest that RNF13 is involved in the regulation of the SNARE complex, which thereby controls synaptic function.     

Physical exercise stimulates marked concomitant release of beta-endorphin and adrenocorticotropic hormone (ACTH) in peripheral blood in man

ACTH and beta-endorphin have been evaluated by means of a specific and sensitive radioimmunoassay in athletes reaching a status of physical stress. A concomitant marked increase of these 2 peptides has been recorded. The implications of this finding lead to the conclusion that stress stimulates the synthesis of the common precursor (31 K) in the pituitary.     

If phosphatases go up, memory goes down

Previous work has provided conclusive support for a role of various protein kinases in processes underlying learning and memory formation. While these processes are not yet established in full detail, it is interesting to entertain the idea of protein phosphatases being involved in such mechanisms as well. Recent advances in this respect have provided preliminary support of this view. From the pharmacological as well as the transgenic analysis, it appears that especially the calcineurin/inhibitor-1 cascade plays an important role in the transition of intermediate-term into long-term memory formation.     

Is it a short‐memory,long‐memory,or permanently Granger‐causation influence?

Exploring the Granger‐causation relationship is an important and interesting topic in the field of econometrics. In the traditional model we usually apply the short‐memory style to exhibit the relationship, but in practice there could be other different influence patterns. Besides the short‐memory relationship, Chen (2006) demonstrates a long‐memory relationship, in which a useful approach is provided for estimation where the time series are not necessarily fractionally co‐integrated. In that paper two different relationships (short‐memory and long‐memory relationship) are regarded whereby the influence flow is decayed by geometric, or cutting off, or harmonic sequences. However, it limits the model to the stationary relationship. This paper extends the influence flow to a non‐stationary relationship where the limitation is on ?0.5 ≤ d ≤ 1.0 and it can be used to detect whether the influence decays off (?0.5 ≤ d < 0.5) or is permanent (0.5 ≤ d ≤ 1.0). Copyright © 2008 John Wiley & Sons, Ltd.     

The spatial orientation of desert ants,Cataglyphis bicolor,before sunrise and after sunset

Zusammenfassung Nachts orientiert sich die WüstenameiseCataglyphis bicolor vorweigend anemomenotaktisch. Einerseits kann jedoch in Mondnächten bei Lichtintensitäten < 1 Lux eine Astrotropotaxis nach dem Mondazimut (positive oder negative Phototaxis) die Windorientierung ausschalten. Andererseits dominiert bei Lichtintensitäten > 350 Lux (ca. 30 min vor Sonnenauf-und nach Sonnenuntergang) die astromenotaktische Orientierung nach dem Polarisationsmuster über die Anemomentoaxis. Wegen der Spiegelsymmetrie des Polarisationsmusters bei horizontnahem Stand der Sonne treten in diesem Zeitintervall bimodale Laufverteilungen auf, die jedoch bei Sonnensicht sofort in unimodale übergehen.     

The data measurement process for UK GNP: stochastic trends,long memory,and unit roots

Much published data is subject to a process of revision due, for example, to additional source data, which generates multiple vintages of data on the same generic variable, a process termed the data measurement process or DMP. This article is concerned with several interrelated aspects of the DMP for UK Gross National Product. Relevant questions include the following. Is the DMP well behaved in the sense of providing a single stochastic trend in the vector time series of vintages? Is one of the vintages of data, for example the ‘final’, the sole vintage generating the long‐memory component? Does the multivariate framework proposed here add to the debate on the existence of a unit root in GNP? The likely implicit assumptions of users (that the DMP is well behaved and the final vintage is ‘best’) can be cast in terms of testable hypotheses; and we show that these ‘standard’ assumptions have not always been empirically founded. Copyright © 2002 John Wiley & Sons, Ltd.     

Anxiety and learning in rats under stress-avoidance-discrimination conditions as influenced by chlorpromazine,reserpine, and glutamate

Zusammenfassung Ein neuer Apparat wird beschrieben, in welchem die Wirkungen von Chlorpromazin, Reserpin und Natriumglutamat auf Furcht und Lernen in Ratten untersucht wurden.     

Physical,Human and Divine attraction in the life and thought of George Cheyne

This paper is a study of the mental environment of the Newtonian conception of attraction in the case of George Cheyne, M.D. (1671–1743), physician of the early 18th century and author of a number of popular medical works. It traces the growth of his notions of a spiritual attraction between God and his creatures and between the creatures themselves, and the relation of these ideas both to his use of the Newtonian model of short-range attraction, and to his conception of the creatures as reflections of the divine essence. The paper contends that the development of these aspects of Cheyne's thought harmonizes with the changing pattern of his life, and that this harmony is expressed by his general technique of reasoning by analogy between the various spheres of experience.     

Physical stress and emetine cardiotoxicity

Résumé Nous rapportons ici des expériences sur le cobaye se rapportant à la toxicité de l'émétine pour le cur, en particulier après potentialisations par de exercices de nage.     

Physical growth and brain development of captive-bred male and female squirrel monkeys,Saimiri sciureus

Summary The physical growth and brain development of the captive bred male and female squirrel monkeys have shown that the male grows at a significantly faster rate with respect to these parameters in the postnatal life, starting from preweaning stage as compared to the female infant. During the prenatal life the male and the female fetuses grow at similar rates and show comparable brain development as indicated by its weight.Acknowledgments. This work was supported by USPHS Grants RR-00165 and HD-06087 from National Institutes of Health. The technical assistance of Mrs Judie Wells is greatly appreciated.     

Issues surrounding sleep-dependent memory consolidation and plasticity

There is a growing body of evidence in support of sleep-dependent memory consolidation and plasticity. However, there are also examples of memory development and plasticity in the absence of sleep, casting doubt on an exclusive sleep-dependent memory hypothesis. As a result, polarized stances have arisen within the field. Here we reflect on these findings, and explore how they maybe reconcilable in a unified approach to understanding the roles of wake, sleep and specific sleep stages in successful memory processing and brain plasticity.Received 6 August 2004; received after revision 28 September 2004; accepted 5 October 2004